1. Field of the Invention
The present invention is directed to an anti-theft device and, more particularly, to a system which permits driver and passenger entry into a locked vehicle without the use of keys, while at the same time maintaining a high degree of security for the vehicle.
2. Description of the Prior Art
Several electrical systems have been devised for automotive vehicles, which allow persons knowledgeable of a predetermined combination to unlock a vehicle by entering that combination into an electronic switch keyboard mounted on the outside of the vehicle.
U.S. Pat. No. 3,544,804 discloses a system utilizing keyboards respectively mounted on the outside of the driver's door and on the dash. The keyboards each have numbered keys or pushbuttons which, when depressed, actuate corresponding switches. The switches, in turn, operate relay components of a register. When the proper combination is formed by sequential actuation of the keys, a lock release solenoid in the door, in the case of the door keyboard, or the starter circuit of the vehicle engine, in the case of the dash keyboard, may be respectively energized to open the door or start the vehicle. The electrical connection between particular pushbuttons of the keyboard and the sequentially actuated relays may be physically changed through the use of a plug and jack patch panel, located in the trunk of the vehicle, to effect a combination change.
U.S. Pat. No. 3,691,396 discloses an electronic combination door and ignition lock which requires insertion of a predetermined code containing repeated symbols from a keyboard unit mounted on the exterior of the vehicle in order to obtain entry to the vehicle. As above, a second keyboard is contained within the vehicle to allow energization of the ignition system of the vehicle upon the reinsertion of the same predetermined code. The system includes a hard wired logic network that gates through a predetermined sequence of keyboard entered digits and resets the system when any digit is entered, which is out of the predetermined sequence.
Both of the prior art patents, discussed above, are rigidly set up so as to cause deactivation (resetting) of the respective systems, when any error is made while entering a single predetermined combination of digits. Those patents are further limited in the number of functions that are possible to be performed while outside the vehicle and do not provide for a reprogrammable system to supplement a permanently programmed system.